Question: Find the value of $x$ such that $\sqrt{1 - 3x} = 7$.
Explanation: Squaring both sides of the equation $\sqrt{1 - 3x} = 7$, we get $1 - 3x = 7^2 = 49$, so $x = (1 - 49)/3 = -48/3 = \boxed{-16}$.